1. Field of the Invention
This invention relates to a method of manufacturing a chain of coupling elements for slide fasteners and has particular reference to a method of forming a chain of such coupling elements from a monofilamentary material having a semi-circular cross-section into a meandering or zig-zag structure.
2. Prior Art
A prior art of the character described is disclosed for example in Japanese Patent Publication No. 39-9390 in which a cross-sectionally semi-circular monofilament is formed into a continuous meandering coupling element structure for mounting astride a longitudinal edge of each of a pair of stringer tapes. Although this prior publication fails to disclose any specific method of making such slide fastener coupling elements, it is believed that a monofilamentary material is spun, formed into an elongated cross-sectionally semi-circular monofilament and wound on a bobbin, from which the monofilament is supplied to a conventional apparatus for forming continuous rows of coupling elements having a meandering or zig-zag configuration. However, being semi-circular in cross-section, the monofilament is apt to become twisted or otherwise deformed when taken up on the bobbin, and it is extremely difficult, if not impossible, to correct the deformed posture of the monofilament so that its cross-sectional shape is reoriented and aligned on processing through the forming apparatus, leading to defective coupling element products.